This proposal concerns the development of two new synthetic methods. Both methodologies involves the use of tandem organo- silicon and sulfur chemistries and their applications to the Diels- Alder reaction. It is proposed to demonstrate the generality and versatility of these new methods by applying them to the synthesis of complex polyfunctional molecules. The first method proposed is new acetylene eqivalent for the Diels-Alder reaction. It is well known that acetylene is a poor diemophile and it is thus desirable to develop an equivalent for this reaction. Currently available equivalents have certain limitations, it is hoped that 1-benzenesulfony 1-2- trimethylsilylacetylene, the equivalent proposed here, will overcome these problems. This equivalent also has the potential advantage of functioning as a mono- and di- substituted acetylene equivalent that displays high regioselectivity. The second synthetic method involves development of a new ketene equivalent for the Diels-Alder reaction. This ketene equivalent is expected to have several advantages over currently available equivalents, it should be easily prepared and have a long shelf life, be relatively reactive in cycloadditions, easily elaborated to ketone functionality, and have no hazardous properties. More especially it is anticipated that this new ketene eqivalent will be capable of acheiving considerable asymmetric induction.